The United States carried out a covert cyber operation against Iran following the Sept. 14 attacks on Saudi Arabia's oil facilities, two US officials told Reuters.
The sources, who requested anonymity, said the operation took place at the end of September and aimed at Iran's ability to spread "propaganda".
The attack affected equipment, according to one of the authorities heard by the news agency, but gave no further details.
The attack emphasizes how President Donald Trump's government has been trying to counter what it sees as Iranian aggression without triggering a wider conflict.
The US and Saudi governments consider Iranians to be responsible for the attacks on oil and gas facilities.
Asked about the Reuters report on Wednesday (16), Iranian Minister of Communications and Information Technology Mohammad Javad Azari-Jahromi replied: "They must have dreamed it," as Fars news agency reported.
The US strike appears to be more limited than other such operations against Iran this year following the collapse of a US drone in June and an alleged Iranian Revolutionary Guard attack on tankers in the Persian Gulf in May.
- Iran toppled US drone in oil-sensitive region
- Iran announces detention of two tankers in Strait of Hormuz
The United States, Saudi Arabia, the United Kingdom, France and Germany attributed the September 14 attacks publicly to Iran, which denied involvement in the action. Yemen's Houthi militant group, Tehran's ally, took responsibility.
Publicly, the Pentagon responded by sending thousands of additional troops and equipment to bolster Saudi defenses – the latest US mobilization in the region this year.
The Pentagon declined to comment on the cyber attack.
Least provocative option
It may take months to determine the impact of the action if there has been one, but cyber attacks are seen as a less provocative option that prevents the outbreak of war.
"You can do damage without killing people or blowing things up; it adds an option to the package we didn't have before, and our willingness to use it is important," said James Lewis, a cyber expert at the Center for Strategic and International Studies, based in Washington.
Lewis added that it may not be possible to halt Iranian behavior even with conventional military attacks.